The present invention relates to steering systems for use with trains of vehicles that roll on wheels without engaging rails for guidance. One particular application is in continuous haulage systems that employ a series of mobile conveyors for moving such as coal or other mined material from underground mines. In room and pillar underground mining locations, a conveyor train may be required to advance and return along a curved or serpentine course during the mining operation. Consequently, true tracking of one vehicle behind another is of great importance in both forward and reverse movement of the conveyor train vehicles. Other important applications may include trains of vehicles carrying luggage at airports, etc. and trains conveying goods into and out of warehouse storage.
Early prior steering systems for trains of vehicles have involved the wagon or Bogie system in which the front wheels of each vehicle are mounted on a common axle pivoted at its center with a steering bar connection to the preceding vehicle. Jackknifing and skidding are common in such systems. King-pin steering systems along with various adaptations to improve tracking have been attempted. A double knuckle has been incorporated in steering linkages between fore and aft vehicles with means to hold either knuckle rigid. However, a change in the rigid and flexible knuckle is required in changing from forward to reverse. Connection between fore and aft wheels on a common vehicle have been incorporated to provide equal turns in opposite directions as the vehicle is steered.
In other systems, an array of wheel axles are connected by cross-bars and stabilized by springs between adjacent axles. The springs lie outside the cross-bar links and stretch or compress to accommodate and stabilize motion during turns. This system would appear to allow the vehicle tires to skid or roll on their rims. Slack in the linkage also may permit deflection.
Bridge carrier systems have been used in which alternate vehicles are controlled by an operator. Slender conveyors form bridges between the controlled vehicles so that the material can be cascaded along the series of conveyors carried by the controller vehicles and bridges. However, when more than two or three operated vehicles become necessary, coordination between operators becomes complicated. Bridge conveyors often use long conveyor unit vehicles to maximize conveying distance with fewer operators. Consequently, the space required for turns is lengthened.